This invention relates to a novel process for the production of polyurethane polymers and to the novel polyurethane polymer products derived from said process. More particularly this invention is directed to a process for preparing particulate thermoplastic polyurethane polymers and to the particulate polymers derived from said process.
Thermoplastic polyurethane polymers constitute a broad class of polymeric materials that are well known in the art and have a wide range of utility. Such polymers are essentially uncrosslinked and are conventionally produced through the interaction of a diisocyanate, a dihydric compound having two active hydrogen atoms in its structure such as polyethers or polyesters, and a chain extending agent also having two active hydrogen atoms in its structure such as an organic diol or diamine. Normally said polyurethane polymers are produced in slab form or some other form not suitable for use in application techniques employed with powdered type resins such as polyethylene. Such techniques include e.g. flame coating, heated substrate coatings, rotational coating, calendering, powder blending with other polymers, sintered shaped articles and coatings, and the like. Consequently such conventional types of thermoplastic polyurethane products have to undergo a reduction in particle size in order to be utilized in such application techniques. While the polyurethane polymer may be reduced in particle size by various expendiences such as grinding, chipping, dicing, etc., such methods result in coarse, non-uniform final products, are time consuming, and have other numerous obvious economic drawbacks. Thus there is a definite need in the art for a process that will produce thermoplastic polyurethane polymers in particulate form.
It has now been discovered that particulate thermoplastic polyurethane polymers can indeed be produced by the process of the instant invention which comprises contacting and reacting an organic dihydric containing compound, an organic diisocyanate, a difunctional organic chain extending agent and an organic interfacial agent in the presence of an inert organic vehicle in which the resulting particulate thermoplastic polyurethane polymer is essentially insoluble.